In conventional computer systems, images are displayed on a two-dimensional screen. The images are defined by arrays of pixels which are either stored in computer memory or received from sources connected to the computer system.
Many images of physical objects may be defined three-dimensionally and may be stored or received as three-dimensional arrays. In recent years, efforts have been undertaken to utilize three-dimensional data to create screen images, also referred to as virtual reality images, that give the illusion of depth. One of the problems associated with production of virtual reality images is determining what objects or portions of objects are within a field of vision seen by a user. For instance, the screen may be considered to be a window or doorway and the user may be considered an observer looking through the window or doorway into a room or outside. The images displayed on the screen represent the images within the field of vision of the observer. In order to produce a field of vision image on a two-dimensional display screen, an efficient method and apparatus for coordinating the use of array elements the physical registers is needed.